U.S. patent number 4,733,692 [Application Number 06/868,995] was granted by the patent office on 1988-03-29 for tube coupling.
This patent grant is currently assigned to Nitto Kohki Co., Ltd. Invention is credited to Naoyuki Kotake, Toshio Mikiya.
United States Patent |
4,733,692 |
Kotake , et al. |
March 29, 1988 |
Tube coupling
Abstract
A tube coupling having a socket and a plug, each having a fluid
flow passage extending therethrough, and a valve mounted in the
flow passage of at least one of the socket and plug for axial
movement between a first position for closing the flow passage and
a second position for opening the flow passage said valve being
normally biased towards the first position by a spring when the
socket and plug are disconnected, and moved to the second position
when the socket and plug are coupled together, characterized in
that at least those portions of the socket and plug which will be
exposed to fluid during the use are formed of fluorocarbon resin,
the spring being disposed in said flow passage and comprising
bellows made of fluorocarbon resin having continuous helically
extending pleats.
Inventors: |
Kotake; Naoyuki (Tokyo,
JP), Mikiya; Toshio (Tokyo, JP) |
Assignee: |
Nitto Kohki Co., Ltd (Tokyo,
JP)
|
Family
ID: |
13749259 |
Appl.
No.: |
06/868,995 |
Filed: |
May 30, 1986 |
Foreign Application Priority Data
|
|
|
|
|
May 30, 1985 [JP] |
|
|
60/81545[U] |
|
Current U.S.
Class: |
137/614.13;
137/614.03; 251/335.3; 267/122 |
Current CPC
Class: |
F16L
37/23 (20130101); F16L 37/34 (20130101); F16L
37/35 (20130101); Y10T 137/87949 (20150401); Y10T
137/87997 (20150401) |
Current International
Class: |
F16L
37/23 (20060101); F16L 37/35 (20060101); F16L
37/00 (20060101); F16L 37/34 (20060101); F16L
37/28 (20060101); F16L 029/00 () |
Field of
Search: |
;137/614,614.03
;251/337,335.3 ;267/152,153,122,123,166 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Chambers; A. Michael
Assistant Examiner: Fox; John C.
Attorney, Agent or Firm: Poff; Clifford A. Murray; Thomas
H.
Claims
We claim:
1. A tube coupling of the type having a socket and a plug, each
having a fluid flow passage extending therethrough, and valve means
mounted in the flow passage through at least one of the socket and
plug for axial movement between a first position for closing said
flow passage and a second position for opening said flow passage,
said valve means being normally biased towards said first position
by spring means when said socket and plug are disconnected, and
adapted to be moved to said second position when the socket and
plug are coupled together, characterized in that at least those
portions of said socket and plug which will be exposed to fluid
during the use are formed of fluorocarbon resin, said spring means
being disposed in said flow passage and comprising bellows made of
fluorocarbon resin having continuous helically extending pleats.
Description
TECHNICAL FIELD
This invention pertains generally to a tube coupling comprising a
socket and plug such as a fluid tube coupling having valve means
which is spring-biased to be moved to its closed position when the
coupling is disconnected and adapted to be moved to its open
position when the coupling is connected, and particularly to such
tube coupling having high chemical resistance and good sealing
properties.
BACKGROUND ART
Tube couplings comprising a socket and plug have been made of metal
or plastics depending upon the application intended. However, there
is still much to be desired with respect to anti-corrosion
properties, temperature resistance and sealing properties.
Valve means for opening and closing flow passage means through the
socket and/or plug is usually arranged to be biased toward its
closed position by a compression coil spring made of metal and to
be retracted to its open position against the biasing force of the
coil spring when the tube coupling is connected. However, being
made of metal, conventional compression coil springs had the
disadvantage that they are susceptible to rust and corrosion as
they are exposed to fluid. There is thus a room for improvement on
resistance to chemicals and corrosion.
Seal rings are usually mounted in the interior of the socket and/or
plug to prevent fluid leakage due to lack of sealing integrity.
However, such seal rings usually formed of rubber have weak points
with respect to resistance to chemicals, corrosion and temperature.
There have been no tube coupling that is suitable for use to handle
fluids containing corrosive chemicals such as strong acids.
DISCLOSURE OF INVENTION
In view of the foregoing drawbacks to the prior art tube coupling,
an object of the present invention is to provide a tube coupling
which is not adversely affected by a fluid being handled if the
fluid contains chemicals or whether it may be at a high or low
temperature, and which may be used with fluid which is averse to
exposure to metal.
It is another object of this invention to provide such tube
coupling which provides increased sealing properties.
In order to accomplish the aforesaid objects, the present invention
according to one aspect thereof provides a tube coupling having a
socket and a plug characterized in that at least those parts of the
socket and plug which will be exposed to fluid are formed of
fluorocarbon resin.
It has been found that since at least those parts of the socket and
plug which are expected to be contacted by fluid are made of
fluorocarbon resin such as PTFE or PFA, the tube coupling according
to this invention provides high resistance to corrosion or attack
by corrosive chemicals, special washing fluids because of the
nature of fluorocarbon resin as well as high resistance to
temperature and weather. While it is known to form a tube coupling
of common plastic materials such as polyamide, polyester or the
like, this invention is the first to provide a tube coupling made
of fluorocarbon resin, as far as the present inventors know.
According to a second aspect, the invention provides a tube
coupling having a socket, a plug and valve means mounted in a flow
passage through at least one of the socket and plug for axial
movement between a first position for closing the flow passage and
a second position for opening the flow passage, said valve means
being normally biased towards said first position by compression
spring means when said socket and plug are disconnected, and
adapted to be moved to said second position when the socket and
plug are coupled, characterized in that at least those parts of
said socket and plug which will be exposed to fluid are formed of
fluorocarbon resin, said compression spring means comprising
bellows formed of fluorocarbon resin.
According to this feature of the invention, not only at least those
parts of the socket and plug expected to be contacted by fluid are
made of fluorocarbon resin such as PTFE or PFA, but also the
compression spring is comprised of bellows of similar fluorocarbon
resin, so that if a fluid which is averse to exposure to metal
contacts with the spring, the fluid is not adversely affected, nor
is the spring affected by the fluid.
As indicated above, because of its high resistance to corrosion and
chemical attack the tube coupling according to this invention is
most suitable for use with fluid, particularly chemicals containing
fluid, corrosive and errosive washing luquid or other liquid. In
addition, since fluorocarbon resin is also superior in resistance
to temperature and weather, the tube coupling finds a wide range of
applications, and may also be used with fluid which is averse to
contact with metal.
Furthermore, the fluorocarbon resin such as PTFE or PFA of which
the coupling is made has anti-friction properties, eliminating the
need for applying grease to seal rings used. In this regard as
well, the tube coupling of this invention is suitable for use with
not only chemicals containing fluid but also pure water or liquid
food products.
When the compression spring is made of fluorocarbon resin such as
PTFE or PFA, the advantages as stated above may be produced.
However, the bellows formed of fluorocarbon resin has the
disadvantage in practical use in that it has a low coefficient of
elasticity in lateral directions as compared to conventional metal
coil springs, requiring in increasing the wall thickness and or
diameter of the bellows in order to provide the same level of
loading as that obtained by comparable metal coil springs.
Accordingly, in a third aspect of the invention this problem is
overcome by providing the bellows of fluorocarbon resin in the form
of special bellows configuration having continuous helically
extending pleats. The fluorocarbon resin made compression spring in
the form of peculiar bellows having continuous helically extending
pleats is axially compressed under compressive force just as a
usual metal coil spring is compressed under compressive load
because the pleats of the bellows are helical, and provides no less
valve closing power than the conventional metallic coil spring and
yet maintains the valve closing power for an extended period time
with repeated operations of connecting and disconnecting the tube
coupling. In addition, owing to its configuration having helical
pleats, the peculiar bellows type spring is less susceptible to
permanent set in fatigue as compared to the usual bellows type
spring and may accommodate variation in loading simply by changing
the wall thickness of the bellows without the need for varying the
diameter of the bellows. Of course, the peculiar bellows type
spring, being formed of fluorocarbon resin, is also free from
degradation due to chemical attack as is the case with metallic
springs, and is highly chemical and corrosion resistant.
According to a fourth aspect, this invention provides a tube
coupling having a socket and a plug, at least one of the socket and
plug being composed of at least two cylindrical members,
characterized in that at least those parts of said socket and plug
which will be exposed to fluid are formed of fluorocarbon resin,
said two cylindrical members being formed of fluorocarbon resin
having different hardnesses, the relatively harder cylindrical
member being formed with an annular angular ridge on the surface
confronting the less hard cylindrical member so that said ridge
bites into the confronting surface of the less hard cylindrical
member to establish a seal therebetween when the two cylindrical
members are assembled together.
According to this construction, since the harder annular angular
ridge bites into the opposing surface of the less hard cylindrical
member to form a seal therebetween, there is no need for disposing
seal rings of less chemical-resistant rubber between the two
cylindrical members as is the case with the prior art tube
coupling.
In an alternate embodiment of the invention, a tube coupling is
provided comprising a socket and a plug, each including at least
one cylindrical member, characterized in that the cylindrical
members of said socket and plug being formed of fluorocarbon carbon
of different hardnesses, the relatively harder cylindrical member
being formed with an annular angular projection on the surface
confronting the less hard cylindrical member so that said harder
projection is brought into sealing contact with the confronting
surface of the less hard cylindrical member when the socket and
plug are coupled together.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and features of the present invention will
be more fully disclosed in the following description, reference
being had to the accompanying drawings, in which:
FIG. 1 is a side view, partly in cross-section, of the tube
coupling according to one embodiment of the present invention
showing the coupling being disconnected;
FIG. 2 is a view similar to FIG. 1 but showing the coupling being
connected;
FIG. 3 is a side view, partly in cross-section, of the tube
coupling according to another embodiment of the present
invention;
FIG. 4 is a side view, partly in cross-section, of the tube
coupling according to still another embodiment of this
invention;
FIG. 5 is a side view similar to FIG. 4 but illustrating the
coupling being connected.
Like parts are indicated by like reference numbers throughout the
drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIGS. 1 and 2, a tube coupling according to one
embodiment of the invention is shown comprising a socket 1 and a
plug 17.
The socket 1 basically comprises an outer cylindrical member 2a and
an inner cylindrical member 2b fitted one over the other and
defining a flow passage 3 therethrough. A solid cylindrical valve
seat member is disposed in and coaxially with the flow passage and
secured to the cylindrical members 2a, 2b by means of a mounting
element 7. The seat member 4 has a valve pushing front face 5 and a
valve seat 6 behind the front face. Surrounding the valve seat
member 4 and axially slidably mounted on a portion of the interior
wall of the inner cylindrical member 2b is a cylindrical valve
member 8 which is movable between a closed position in which it is
in sealing contact with the valve seat 6 to close the flow passage
3 and an open position in which the valve member is retracted away
from the valve seat 6 to open the flow passage.
According to this invention, at least those portions of the socket
1 which will be expected to be exposed to fluid during the use,
which are the cylindrical members 2a, 2b, valve seat member 4,
mounting piece 7 and valve member 8 in the illustrated embodiment
are formed of fluorocarbon resin. Those portions may entirely be
made of fluorocarbon resin. Alternatively, only the surfaces of
said portions which will be exposed to fluid may be coated with
fluorocarbon resin.
Fluorocarbon resins suitable for use in this invention may include
PTFE (polytetrafluoroethylene) and PFA
(tetrafluoroethylene-perfluoroalkylvinylether copolymer). PVDF
(polyvinylidene fluoride) having good workability may also be
used.
That portion of the inner wall 9 of the inner cylindrical member 2b
which opposes the central part of the valve member 8 intermediate
its opposite ends is spaced radially outwardly from the central
outer periphery of the valve member to define a space therebetween
in which a compression spring 10 surrounding the central periphery
of the valve member 8 is disposed under compression between a
shoulder formed on the cylindrical member and a shoulder on the
valve member to bias the valve member 8 toward the valve seat 6.
According to a preferred embodiment of this invention, the
compression spring 10 may comprise bellows formed of fluorocarbon
resin.
11 is a seal ring disposed between the interior wall of the inner
cylindrical member and the outer periphery of the rear end portion
of the valve member 8; 12 are locking balls engageable with an
outer peripheral groove 27 formed in a plug 17 as will be described
below to lock the socket and plug in their coupled position; 13 is
a sleeve for depressing the locking balls; 14 is a compression
spring for urging the sleeve 13 toward its ball-depressing
position; and 15, 16 are seal rings.
The plug 17 comprises an outer cylindrical member 18a and an inner
cylindrical member 18b fitted one over the other and defining a
flow passage 19 therethrough. A valve member 20 is disposed in the
flow passage 19 and axially slidably mounted on the inner walls of
the cylindrical members 18a, 18b. The valve member 20 comprises a
cylindrical portion 22 having a bore 21 opening at its rear end
into the flow passage 19 and closed at its fore end by a disc-like
valve head. The bore 21 is in communication with the exterior of
the cylindrical portion 22 via ports 31 formed through the
cylindrical portion adjacent its fore end.
According to this invention, at least those portions of the plug 17
which will be exposed to fluid during the use, which are the
cylindrical members 18a, 18b and the valve member 20 in the
illustrated embodiment are formed of fluorocarbon resin. Those
portions may entirely be formed of such resin. Or alternatively,
only those surfaces of said portions which will contact with fluid
may be lined with coatings of fluorocarbon resin.
The valve member 20 is movable between a closed position in which
it is in sealing contact with a valve seat 32 formed on the inner
wall of the outer cylindrical member 18a to close the flow passage
19 and an open position in which it is disengaged from the valve
seat 32 to open the flow passage. That portion of the inner wall 24
of the outer cylindrical member 18a which opposes the central part
of the cylindrical portion 20 of the valve member 20 intermediate
its opposite ends is spaced radially outwardly from the central
outer periphery of the cylindrical portion 22 to define a space
therebetween in which a compression spring 23 surrounding the outer
periphery of the cylindrical portion 22 is disposed under
compression between the front end face of the cylindrical member
18b and a shoulder on the cylindrical member 18a to bias the valve
member 20 toward the valve seat 32. According to a preferred
embodiment of this invention, the compression spring 23 may
comprise bellows formed of fluorocarbon resin.
25 and 26 are seal rings disposed between the inner walls of the
outer and inner cylindrical members 18a and 18b and the outer
periphery of the cylindrical portion 22 of the valve member; 27 is
an annular peripheral groove formed in the outer cylindrical member
18a with which the locking balls 12 are engageable when the socket
and plug are coupled together; and 28, 29 are seal rings.
When the socket 1 and plug 17 are coupled together as shown in FIG.
2, the front end of the outer cylindrical member 18a of the plug 17
pushes the valve member 8 of the socket to the open position
against the biasing force of the spring 10 while at the some time
the front valve pushing face 5 of the valve seat member 4 pushes
the valve member 20 of the plug 17 to the open position against the
biasing force of the spring 23. The flow passages 3 and 19 of the
socket 1 and plug 17 are thus opened and communicated with each
other.
FIG. 3 illustrates a tube coupling according to another embodiment
of this invention. This tube also comprise a socket 1 and a plug
17.
The socket 1 comprises a main cylindrical body 2 having a flow
passage 3 extending therethrough. Axially slidably mounted in the
flow passage 3 is a generally cylindrical valve member 54 for
opening and closing the flow passage. The valve member 54 comprises
a cylindrical portion 55 and a valve head portion or closed front
end portion 56, said cylindrical portion being formed with radial
fluid ports 57 adjacent the head portion 56. The main cylindrical
body 2 has an inner annular protuberance 58 defining a valve seat
with which the valve head portion 56 is adapted to be in sealing
engagement to close the flow passage 3 in a conventional
manner.
A compression spring 59 is compressed between the main cylindrical
body 2 and the valve member 54 to urge the latter into abutment
with the valve seat 58.
According to this invention, at least those portions of the socket
1 which will be exposed to fluid during the use, which are the main
cylindrical member 2, valve member 54 and compression spring 59 in
the illustrated embodiment are formed of fluorocarbon resin.
Furthermore, according to the teachings of the present invention,
the compression spring 59 comprises a specially-shaped bellows made
of fluorocarbon resin having continuous helical pleats or
convolutions, instead of conventional simple bellows. One end
portion of the compression spring 59 is inserted in the cylindrical
portion 55 of the valve member 54 and retained against a shoulder
60 formed on the inner periphery of the cylindrical portion 55
while the other end portion of the spring is accommodated in a
tubular spring holder 61 fitted in and fixed to the flow passage 3
and is retained against a shoulder 62 formed around the inner
periphery of the spring holder 61. The rear open end of the
cylindrical portion 55 of the valve member 54 is normally spaced
away from the opposed open end of the spring holder 61 to define
therebetween a gap 63 for permitting retraction of the valve 54 to
open the flow passage 3 when the socket 1 and plug 17 are coupled
together as will be described hereinafter.
64 is a snap ring to retain the spring holder 61. Locking balls 12
are adapted to lockingly engage a circumferential groove 27 formed
around the outer periphery of the plug 17 when the plug is inserted
into the socket 1. Axially slidably fitted over the socket 1 is a
sleeve 13 having an internal annular protrusion which is urged by a
spring 14 into engagement with the locking balls 12 to press the
balls downwardly. The socket has a seal ring 68 adapted to contact
the outer periphery of the plug 17 to provide a seal therebetween
when the plug is received in the socket.
The plug 17 comprises a main cylindrical body 18 having a flow
passage 19 extending therethrough. Axially slidably mounted in the
flow passage 19 is a generally cylindrical valve member 20 for
opening and closing the flow passage 19. The valve member 20
comprises a cylindrical portion 22 and a valve head portion or
closed front end portion 74, said cylindrical portion being formed
with radial fluid ports 31 adjacent the head portion 74. The main
cylindrical body 18 has an inner annular protuberance 32 defining a
valve seat with which the valve head portion 74 is adapted to be in
sealing engagement to close the flow passage 19 in the same manner
as with the socket 1.
A compression spring 77 is compressed between the main cylindrical
body 18 and the valve member 20 to urge the latter into abutment
with the valve seat 32.
According to the present invention, at least those portions of the
plug 17 which will be in contact with fluid during the use, which
are the main cylindrical body 18, valve member 20 and compression
spring 77 in the illustrated embodiment, are formed of fluorocarbon
resin, as with the socket 1.
Furthermore, according to the present invention, the compression
spring 77 comprises a specially--shaped bellows made of
fluorocarbon resin having continuous helical pleats or
convolutions, as with the compression spring 59 in the socket 1.
One end portion of the compression spring 77 is inserted in the
cylindrical portion 22 of the valve member 20 and retained against
a shoulder 78 formed on the inner periphery of the cylindrical
portion 22 while the other end portion of the spring 77 is
accommodated in a tubular spring holder 79 fitted in and fixed to
the flow passage 19 and is retained against a shoulder 80 formed
around the inner periphery of the spring holder 79. The rear open
end of the cylindrical portion 22 of the valve 20 is normally
spaced away from the opposed open end of the spring holder 79 to
define therebetween a gap 81 for permitting retraction of the valve
20 to open the flow passage 19 when the socket 1 and the plug 17
are coupled together.
It is to be understood that upon the tube coupling being connected,
the two opposed valve members 54 and 20 abut against each other and
are both retracted to their open positions against the biasing
forces of their respective springs 59 and 77 to open the flow
passages 3 and 19 and provide communication therebetween.
When the socket and plug are coupled together, the locking balls 12
are depressed into the circumferential groove 27 to hold the socket
and plug locked.
In order to disconnect the tube coupling, the sleeve 13 is manually
moved axially inwardly against the force of the spring 14 until the
balls 12 are released. The plug 17 may then be pulled out of the
socket 1 as the balls 12 are moved out of the slot.
FIGS. 4 and 5 illustrate a tube coupling according to this
invention. This tube coupling is similar to that shown in FIGS. 1
and 2 not only in construction but also in that at least those
portions of the socket and plug which will be exposed to fluid are
formed of fluorocarbon resin and that the compression springs 10
and 23 are in the form of bellows made of fluorocarbon resin.
The distinction between the coupling in this embodiment and that
shown in FIGS. 1 and 2 is that in this embodiment the main
cylindrical body of the socket and/or the plug comprises a
plurality of cylindrical members which are formed of fluorocarbon
resins having different hardnesses, the surface of the harder
cylindrical member in confronting relation with the surface of the
less hard cylindrical member being formed with an annular angular
(V-shaped) ridge.
More specifically, the main cylindrical body of the socket 1
comprises a plurality of cylindrical members, that is, an outer
cylindrical member 2a and an inner cylindrical member 2b in the
illustrated embodiment made of fluorocarbon resins having different
hardnesses. Likewise, the main cylindrical body of the plug 17
comprises a plurality of cylindrical members--an outer cylindrical
member 18a and an inner cylindrical member 18b in the illustrated
embodiment made of fluororesin resins having different hardnesses.
The harder cylindrical members 2b and 18a are formed with annular
angular ridges 83 and 84, respectively on the surfaces thereof
confronting with surfaces of the corresponding cylindrical members
2a and 18b.
When the cylindrical members 2a and 2b and the cylindrical members
18a and 18b are assembled together as shown in FIGS. 4 and 5, the
annular angular ridges 83 and 84 on the cylindrical members 2b and
18a, respectively bite into the confronting surfaces of the
cylindrical members 2a and 18a, respectively to establish a seal
therebetween. There is thus no need for providing seal rings
between the cylindrical members, as is the case with the embodiment
shown in FIGS. 1 and 2.
Furthermore, according to the present invention, two opposing
cylindrical members of the socket and plug having surfaces adapted
to be brought into abutting engagement with each other when the
socket and plug are coupled may be formed of fluorocarbon resins
having different hardnesses. Those two cylindrical members are the
cylindrical valve member 8 of the socket and the outer cylindrical
member 18a of the plug in the illustrated embodiment. The harder
cylindrical valve member 8 is formed on its end surface with an
annular angular projection 88 which is adapted to be brought into
biting, engagement with the surface 90 of the cylindrical member
18a to establish a seal therebetween when the coupling is
connected.
It is to be appreciated that this embodiment provides the
additional advantage of eliminating the need for seal rings while
retaining all the advantages provided by the embodiment of FIGS. 1
and 2.
The above description is included to illustrate the preferred
embodiments of the present invention and is not meant to limit the
scope of the invention. The scope of the invention is to be limited
only by the appended claims. From the above description, many
variations will be apparent to one skilled in the art that would be
encompassed by the spirit and scope of the invention.
* * * * *